Organic compounds

ABSTRACT

A pharmaceutical composition for parenteral administration of a somatostatin analogue salt of aspartate, e.g. mono- or diaspartate, lactate, succinate, e.g. mono- or disuccinate, acetate, glutamate, e.g. mono- or diglutamate or citrate and water forming a gelling depot system after injection in contact with the body fluid.

The present invention relates to liquid pharmaceutical compositions, in particular to depot formulations comprising somatostatin analogues and to a process for preparing said depot formulations.

Depot formulations are typically administered parenterally. Somatostatin depot formulations may be administered by injection subcutaneously or intramuscularly through a small gauge needle or placed into accessible tissue sites through a cannula. However parenteral administration may be very painful especially if repeated injections are necessary. Furthermore, there may be difficulties with depot formulations which are administered in liquid form and which form a solid implant in the body after injection. Often the solidifying process starts in the syringe before injection and causes needle clogging.

Further, these depot formulations may comprise a polymer or a mixture of polymers that has to be dissolved in an organic solvent, e.g. they may comprise more than 50 % of an organic solvent. If the organic solvent remains in the solution for injection it might cause severe tissue irritation or necrosis at the site of implantation.

EP 779 805 provides a pharmaceutical composition consisting of a soluble peptide salt which will form a gel upon contact with a body fluid, and up to 30% by weight of the composition of a pharmaceutically acceptable carrier. The peptides described in EP 779805 are somatostatins or a somatostatin analogs, e.g. lanreotide.

Surprisingly it has now been found that advantageous parenteral somatostatin depot formulations may be obtained with a composition comprising a salt of a somatostatin analogue and water having a pH from 3 to 7 without using a polymer and without using an organic solvent.

The present invention provides in one aspect a pharmaceutical composition for parenteral administration comprising a somatostatin analogue salt of aspartate, e.g. mono- or diaspartate, glutamate, e.g. mono- or diglutamate, or succinate, e.g. mono- or disuccinate, lactate, acetate or citrate and water, forming a gelling depot after injection in contact with body fluid. The salt: base ratio of the somatostatin analogue salts may range from 0.1 to 2 and provides the solubility of the somatostatin analogue salt. The pharmaceutical composition has a pH between about 3.0 and 7.0, preferably from between 4.0 and 6.0 and more preferably from between about 4.0 and 5.0. Optionally the composition may comprise a pharmaceutically acceptable buffer in an amount to stabilize the pH between about 3.0 and 7.0, preferably between about 4.0 and 6.0, most preferably between 4.0 and 5.0.

In another aspect the present invention provides a pharmaceutical composition for parenteral administration comprising a somatostatin analogue salt of aspartate, e.g. mono- or diaspartate, glutamate, e.g. mono- or diglutamate, lactate, succinate, e.g. mono- or disuccinate, acetate or citrate, and water, having a pH between about 3.0 and 7.0, forming a gelling depot after injection in contact with body fluid.

The composition having a pH between about 3.0 and 7.0 provides good solubility and therefore the composition of the invention may be stored over an extended period of time without precipitation. The composition is administered to the patient by injection wherein the composition will start to form a gelling depot after and not before interaction with patients body fluid. The gelling depot releases the somatostatin analogue salt of aspartate, lactate, succinate, acetate, glutamate or citrate within the patient over an extended period of time.

In another aspect the invention provides a process for preparing a depot formulation by

-   -   i) dissolving a somatostatin analogue salt of aspartate, e.g.         mono- or diaspartate, lactate, succinate, e.g. mono- or         disuccinate, acetate, glutamate, e.g. mono- or diglutamate or         citrate in water,     -   ii) optionally adding a buffer to stabilize the pH of the         solution, and optionally iii) filling the solution into a         syringe

In a further aspect the invention provides a process for preparing a depot formulation by

-   -   i) dissolving a somatostatin analogue salt of aspartate, e.g.         mono- or diaspartate, lactate, succinate, e.g. mono- or         disuccinate, acetate, glutamate, e.g. mono- or diglutamate, or         citrate in water, having a pH of between 3.0 and 7.0,     -   ii) optionally adding a buffer to stabilize the pH of the         solution, and optionally     -   iii) filling the solution into a syringe

The present invention relates to somatostatin analogue salts of aspartate, e.g. mono- or diaspartate, lactate, succinate, e.g. mono- or disuccinate, acetate, glutamate, e.g. mono- or diglutamate or citrate.

Somatostatin is a tetradecapeptide having the structure

Somatostatin analogues of particular interest have been described e.g. in WO 97/01579 and WO 97/25977. Said somatostatin analogues comprise the amino acid sequence of formula I

-(D/L)Trp-Lys-X₁—X₂—

wherein X₁ is a radical of formula (a) or (b)

wherein R₁ is optionally substituted phenyl, wherein the substituent may be halogen, methyl, ethyl, methoxy or ethoxy,

R₂ is -Z₁CH₂R₁, —CH₂—CO—O—CH₂—R₁,

wherein Z₁ is O or S, and

X₂ is an α-amino acid having an aromatic residue on the C_(α) side chain, or an amino acid unit selected from Dab, Dpr, Dpm, His,(Bzl)HyPro, thienyl-Ala, cyclohexyl-Ala and t-butyl-Ala, the residue Lys of said sequence corresponding to the residue Lys⁹ of the native somato-statin-14.

By somatostatin analogue as used herein is meant a straight-chain or cyclic peptide derived from that of the naturally occurring somatostatin-14, comprising the sequence of formula I and wherein additionally one or more amino acid units have been omitted andlor replaced by one or more other amino acid radical(s) and/or wherein one or more functional groups have been replaced by one or more other functional groups andlor one or more groups have been replaced by one or several other isosteric groups. In general the term covers all modified derivatives of the native somatostatin-14 comprising the above sequence of formula I which have binding affinity in the nM range to at least one somatostatin receptor subtype as defined hereinafter.

Preferably, the somatostatin analogue is a compound in which the residues at positions 8 through 11 of the somatostatin-14 are represented by the sequence of formula I as defined above.

More preferably, the somatostatin analogue is a compound as disclosed above comprising a hexapeptide unit, the residues at positions 3 through 6 of said hexapeptide unit comprising the sequence of formula I. Particularly preferred is a somatostatin hexapeptide wherein the residues at positions 1 and 2 of the hexapeptide unit may be any of those as known in the art, e.g. as disclosed by A. S. Dutta in Small Peptides, Vol. 19, 292-354, Elsevier, 1993, or as substituents for, Phe⁶ andlor Phe⁷ of somatostatin-14.

More particularly the somatostatin analogue is a compound in which the hexapeptide unit is cyclic, e.g. having a direct peptide linkage between the α-carbonyl group of the residue at position 6 and the α-amino group of the residue at position 1.

While Lys, X₁ and X₂ in the sequence of formula I have the L-configuration, Trp may have the D- or L-configuration. Preferably Trp has the D-configuration.

X₁ is preferably a residue of formula (a) or (b), R₂ being preferably

When X₂ comprises an aromatic residue on the C_(α) side chain, it may suitably be a natural or unnatural α-amino acid, e.g. Phe, Tyr, Trp, Nal, Pal, benzothienyl-Ala, Tic and thyronin, preferably Phe or Nal, more preferably Phe. X₂ is preferably an α-amino acid bearing an aromatic residue on the C_(α) side chain.

When R₁ is substituted phenyl, it may suitably be substituted by halogen, methyl, ethyl, methoxy or ethoxy e.g. in ortho and/or para. More preferably R₁ is unsubstituted phenyl.

Z₁ is preferably O.

Representative compounds of the invention are e.g. compounds of formula (II)

cyclo[A-ZZ_(a)-(D/L)Trp-Lys-X₁—X₂]  (II)

wherein

X₁ and X₂ are as defined above,

A is a divalent residue selected from Pro,

wherein R₃ is NR₈R₉—C₂₋₆alkylene, guanidino-C₂₋₆alkylene or C₂₋₆alkylene-COOH, R_(3a) is H, C₁₋₄alkyl or has independently one of the significances given for R₃, R_(3b) is H or C₁₋₄alkyl, R_(a) is OH or NR₅R₆, R_(b) is —(CH₂)₁₋₃— or —CH(CH₃)—, R₄ is H or CH₃, R_(4a) is optionally ring-substituted benzyl, each of R₅ and R₆ independently is H, C₁₋₄alkyl, ω-amino-C₁₋₄alkylene, ω-hydroxy-C₁₋₄alkylene or acyl, R₇ is a direct bond or C₁₋₆alkylene, each of R₈ and R₉ independently is H, C₁₋₄alkyl, ω-hydroxy-C₂₋₄alkylene, acyl or CH₂OH—(CHOH)_(c)—CH₂— wherein c is 0, 1, 2, 3 or 4, or R₈ and R₉ form together with the nitrogen atom to which they are attached a heterocyclic group which may comprise a further heteroatom, and R₁₁ is optionally ring-substituted benzyl, —(CH₂)₁₋₃—OH, CH₃—CH(OH)— or —(CH₂)₁₋₅—NR₅R₆, and

ZZ_(a) is a natural or unnatural α-amino acid unit.

ZZ_(a) may have the D- or L-configuration. When ZZ_(a) is a natural or unnatural α-amino acid unit, it may suitably be e.g. Thr, Ser, Ala, Val, lie, Leu, Nle, His, Arg, Lys, Nal, Pal, Tyr, Trp, optionally ring-substituted Phe or N^(α)-benzyl-Gly. When ZZ_(a) is Phe, the benzene ring thereof may be substituted by e.g. NH₂, NO₂, CH₃, OCH₃ or halogen, preferably in para position. When ZZ_(a) is Phe, the benzene ring thereof is preferably unsubstituted.

When A comprises a Pro amino acid residue, any substituent present on the proline ring, e.g. R₃—NH—CO—O— etc., is preferably in position 4. Such substituted proline residue may exist in the cis form, e.g.

as well as in the trans form. Each geometric isomer individually as well as mixtures thereof are compounds of the invention.

When A is

where NR₈R₉ forms a heterocyclic group, such group may be aromatic or saturated and may comprise one nitrogen or one nitrogen and a second heteroatom selected from nitrogen and oxygen. Preferably the heterocyclic group is e.g. pyridyl or morpholino. C₂₋₆Alkylene in this residue is preferably —CH₂—CH₂—.

Any acyl as R₅, R₆, R₈ and R₉ in A may be e.g. R₁₂CO— wherein R₁₂ is H, C₁₋₄alkyl, C₂₋₄alkenyl, C₃₋₆cycloalkyl or benzyl, preferably methyl or ethyl. When R_(4a) or R₁₁, in A is ring-substituted benzyl, the benzene ring may be substituted as indicated above for ZZ_(a).

Particularly preferred are compounds of formula III

wherein the configuration at C-2 is (R) or (S) or a mixture thereof, and

wherein R is NR₁₀R₁₁—C₂₋₆alkylene or guanidine-C₂₋₆alkylene, and each of R₁₀ and R₁₁ independently is H or C₁₋₄alkyl,

in free form, in salt form or protected form the synthesis of which may be performed as described e.g. in WO 2002/10192 which is hereby incorporated by reference.

The salts are obtained by the process as described e.g. in WO 2002/10192 which is hereby incorporated by reference.

Preferably R is NR₁₀R₁₁—C₂₋₆alkylene. Preferred compounds of formula II are the compounds wherein R is 2-amino-ethyl, namely cyclo[{4-(NH₂—C₂H₄—NH—CO—O-)Pro}-Phg-DTrp-Lys-Tyr(4-Bzl)-Phe] (referred herein to as Compound A) and cyclo[{4-(NH₂—C₂H₄—NH—CO—O-)Pro)-DPhg-DTrp-Lys-Tyr(4-Bzl)Phe], in free form, salt form or protected form. Phg means —HN—CH(C₆H₅)—CO— and Bzl means benzyl.

A salt of the invention in protected form corresponds to a somatostatin analogue wherein at least one of the amino groups is protected and which by deprotection leads to a compound of formula II, preferably physiologically removable. Suitable amino protecting groups are e.g. as disclosed in “Protective Groups in Organic Synthesis”, T. W. Greene, J. Wiley & Sons NY (1981), 219-287, the contents of which being incorporated herein by reference. Example of such an amino protecting group is acetyl.

The composition according to the present invention may comprise a buffer. Suitable buffers include but are not limited to acetate buffer, lactate buffer, glycin buffer and tartrate buffer. The concentrations of the buffers may be from about 5 mM to 30 mM, preferably from about 10 mM to 25 mM.

In a further aspect the invention provides a pharmaceutical composition in a viscous liquid form that may be injected with a syringe through a needle ranging from 18 G to 25 G, e.g. 20 G. The solution may be placed in a syringe after sterile filtration through a 0.2 μm filter having a viscosity of from 1 to 10⁴ mPa·s or after sterile filtration and solvent removal by evaporation or sublimation having a viscosity of from 10² to 10⁶ mPa·s. The solvent removal may be done after placing the solution in the syringe.

The solution in the syringe may be injected through a needle, e.g. a 20 G needle, into the body subcutaneously, intramuscularly, intradermally or intraperitoneally or placed into accessible tissue sites through a cannula. Once in place in contact with the patient's body fluid the gelling depot will be formed. The liquid composition for parenteral administration may be filled in a syringe, preferably a prefilled syringe may be provided together with instructions for use.

In another aspect the invention provides a depot formulation for extended release of the pharmaceutically active agent. The implant formed after injection into the body may release the active agent over an extended period of time. The release period may range from 1 up to 90 days, e.g. 1 up to 60 days, e.g. between 30 to 60 days.

The compositions of the invention are useful for treatment of the known indications of the particular active agent. Compositions of the invention comprising a somatostatin analogue salt of aspartate, lactate, succinate, acetate, glutamate or citrate may be useful in the following indications:

-   -   a) for the prevention or treatment of disorders with an         aetiology comprising or associated with excess GH-secretion         and/or excess of IGF-1 e.g. in the treatment of acromegaly as         well as in the treatment of type I or type II diabetes mellitus,         especially complications thereof, e.g. angiopathy, diabetic         proliferative retinopathy, diabetic macular edema, nephropathy,         neuropathy and dawn phenomenon, and other metabolic disorders         related to insulin or glucagon release, e.g. obesity, e.g.         morbid obesity or hypothalamic or hyperinsulinemic obesity,     -   b) in the treatment of enterocutaneous and pancreaticocutaneous         fistula, irritable bowel syndrom, inflammatory diseases, e.g.         Grave's Disease, inflammatory bowel disease, psoriasis or         rheumatoid arthritis, polycystic kidney disease, dumping         syndrom, watery diarrhea syndrom, AIDS-related diarrhea,         chemotherapy-induced diarrhea, acute or chronic pancreatitis and         gastrointestinal hormone secreting tumors (e.g. GEP tumors, for         example vipomas, glucagonomas, insulinomas, carcinoids and the         like), lymphocyte malignancies, e.g. lymphomas or leukemias,         hepatocellular carcinoma as well as gastrointestinal bleeding,         e.g variceal oesophagial bleeding,     -   c) for the prevention or treatment of angiogenesis, inflammatory         disorders as indicated above including inflammatory eye         diseases, macular edema, e.g. cystoid macular edema, idiopathic         cystoid macular edema, exudative age-related macular         degeneration, choroidal neovascularization related disorders and         proliferative retinopathy,     -   d) for preventing or combating graft vessel diseases, e.g. allo-         or xenotransplant vasculopathies, e.g. graft vessel         atherosclerosis, e.g. in a transplant of organ, e.g. heart,         lung, combined heart-lung, liver, kidney or pancreatic         transplants, or for preventing or treating vein graft stenosis,         restenosis and/or vascular occlusion following vascular injury,         e.g. caused by catherization procedures or vascular scraping         procedures such as percutaneous transluminal angioplasty, laser         treatment or other invasive procedures which disrupt the         integrity of the vascular intima or endothelium,     -   e) for treating somatostatin receptor expressing or accumulating         tumors such as pituitary tumors, e.g. Cushing's Disease,         gastro-enteropancreatic, carcinoids, central nervous system,         breast, prostatic (including advanced hormone-refractory         prostate cancer), ovarian or colonic tumors, small cell lung         cancer, malignant bowel obstruction, paragangliomas, kidney         cancer, skin cancer, neuroblastomas, pheochromocytomas,         medullary thyroid carcinomas, myelomas, lymphomas, Hodgkins and         non-Hodgkins lymphomas, bone tumours and metastases thereof, as         well as autoimmune or inflammatory disorders, e.g. rheumatoid         arthritis, Graves disease or other inflammatory eye diseases.

Preferably, the compositions of the invention are useful in the treatment of acromegaly, carcinoids andlor Cushing's Disease.

The activity and the characteristics of the liquid compositions of the invention may be indicated in standard clinical or animal tests.

Appropriate dosage of the composition of the invention will of course vary, e.g. depending on the condition to be treated (for example the disease type of the nature of resistance), the drug used, the effect desired and the mode of administration.

For compositions of the invention comprising the somatostatin salt of aspartate, lactate, succinate, acetate, glutamate or citrate satisfactory results are obtained on administration, e.g. parenteral administration, at dosages in the order of from about 0.1 to about 100 mg, preferably from about 3 to about 60 mg per injection per month or about 0.01 to about 4 mg preferably 0.1 to 1 mg per kg animal body weight per month, administered once or in divided doses. Suitable monthly dosages for patients are thus in the order of about 0.1 mg to about 80 mg of a somatostatin analogue salt of aspartate, lactate, succinate, acetate, glutamate or citrate.

The present invention provides a simple pharmaceutical composition of somatostatin analogue salt of aspartate, e.g. mono- or diaspartate, lactate, succinate e.g. mono- or disuccinate, acetate, glutamate, e.g. mono- or diglutamate, or citrate in a salt:base ratio ranging from 0.1 to 2 and water at a defined pH between 3.0 to 7.0, preferably between about 4.0 to 6.0, more preferably between about 4.0 to 5.0. The salt base ratio ranging from 0.1 to 2 provides the solubility of the somatostatin analogue salt at a given pH and the precipitation and depot formation after contact with body fluids and therefore environmental pH change. The pH may be stabilized by a buffer. The process to prepare the composition is simple by adding water to the somatostatin analogue salt. At a pH between about 4.0 to 6.0 the composition shows good solubility and therefore precipitation, e.g. in a prefilled, syringe or needle clogging is avoided. No organic solvents that might cause severe side effects at the place of administration are used.

Following is a description by way of example only of processes and compositions of the invention.

EXAMPLE 1

Weight Required Actual Raw materials g weight weight Somatostatin 58.8235  0.8 g  0.8 g diaspartate Water for injection 100 1.36 ml 1.36 ml (WFI)

A 2 ml solution of the pharmaceutical composition of the present invention is made by mixing 0.8 g somatostatin diaspartate with 1.36 ml water for injection.

EXAMPLE 2

Release profile in rabbits of the drug product having the composition given in example 1. The composition has been injected parenterally and blood samples have been taken several times during a period of 2 months to measure the somatostatin diaspartate.

EXAMPLE 3

Raw materials Required weight Actual weight Somatostatin 1.0 g 0.999 g di-succinate Water for injection 1.6 ml  1.6 ml (WFI)

The di-succinate form of the pharmaceutical composition of the present invention is made by mixing 0.999 g somatostatin di-succinate with 1.6 ml water for injection.

EXAMPLE 4

Raw materials Required weight Actual weight Somatostatin 0.916 g 0.916 g di-glutamate Water for injection  1.44 ml  1.44 ml (WFI)

The di-glutamate form of the pharmaceutical composition of the present invention is made by mixing 0.916 g somatostatin di-glutamate with 1.44 ml water for injection.

EXAMPLE 5

Release profile in rabbits of the drug product having the composition given in example 3 and 4. The composition has been injected parenterally and blood samples have been taken several times during a period of 2 months to measure the somatostatin disuccinate and somatostatin diglutamate. 

1. A pharmaceutical composition for parenteral administration comprising a somatostatin analogue salt of mono- or diaspartate, mono- or diglutamate, mono- or disuccinate, acetate or citrate and water forming a gelling depot system after injection in contact with body fluid.
 2. A pharmaceutical composition for parenteral administration comprising a somatostatin analogue salt of mono- or diaspartate, mono- or diglutamtate, lactate, mono- or disuccinate, acetate or citrate and water, having a pH of between 3.0 and 7.0, forming a gelling depot system after injection in contact with body fluid.
 3. The pharmaceutical composition of claim 1 wherein the somatostatin analogue salt has a salt: base ratio ranging from 0.1 to
 2. 4. The pharmaceutical composition according to claim 2 having a pH of between about 4.0 and 6.0.
 5. The pharmaceutical composition according to claim 4 having a pH of between about 4.0 and 5.0.
 6. The pharmaceutical composition according to claim 1 comprising a pharmaceutically acceptable buffer in an amount to provide a pH of between about 3 and
 7. 7. The pharmaceutical composition according to claim 6 having a pH of between about 4.0 and 5.0.
 8. The pharmaceutical composition according to claim 6 wherein the pharmaceutically acceptable buffer is chosen from at least one of an acetate buffer, a tartrate buffer, a glycin buffer and a lactate buffer.
 9. The pharmaceutical composition according to claim 6 wherein the pharmaceutically acceptable buffer is acetate buffer.
 10. The pharmaceutical composition according to claim 9 wherein the acetate buffer is used in a concentration of about 10 mM to 25 mM.
 11. The pharmaceutical composition according to claim 1 wherein said gelling depot system releases somatostatin analogue salt of aspartate, lactate, succinate, acetate, glutamate or citrate continuously within the patient over an extended period of time of from 1 to 90 days.
 12. The pharmaceutical composition of claim 11 wherein said gelling depot system releases somatostatin analogue salt of aspartate, lactate, succinate, acetate, glutamate or citrate continuously within the patient over an extended period of time of from 1 to 60 days.
 13. The pharmaceutical composition according to claim 1 having a viscosity from 1 to 106 mPa s.
 14. A prefilled syringe comprising the composition of claim 1 and instructions to use.
 15. A process to prepare the pharmaceutical composition according claim 1 comprising dissolving a somatostatin analogue salt of mono- or diaspartate, mono- or diglutamate, lactate, mono- or disuccinate, acetate or citrate in water, optionally adding a pharmaceutically acceptable amount of a buffer, and optionally filling the solution into a syringe.
 16. A process to prepare the pharmaceutical composition according to claim 1 comprising dissolving a somatostatin analogue salt of mono- or diaspartate, mono- or diglutamate, lactate, mono- or disuccinate, acetate or citrate in water, adding a pharmaceutically acceptable amount of a buffer to obtain a pH of between 3.0 and 7.0, and optionally filling the solution into a syringe. 